Baphael josta



rrrcn.

ATENT RAPHAEL JOSTA, OF FLORENCE, ITALY, ASSIGNOR TO VILLTAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES 0F LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,514, dated October 3, 1882.

Application filed August 9, 1882. (No specimens.)

To all whom "it may concern:

Be it known that I, RAPHAEL JOSIA, of Florence, Kingdom of Italy, have invented or discovered a new and useful Improvementin Oompositions for Treating Sulphates of Lime for the Manufacture of Artificial Marble; and I do hereby declare the following to be a full, clear, concise, and exact description thereof.

In an application for Letters Patent of the United States filed March 2, 1882, I have de scribed and made claim to an improved process of treating or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles of a material which I have termed certaldite without pulverization of the gyp' sum. In said application I described briefly certain of the compounds or compositions which I employ to produce certain effects and the manner of using, them, but stated that separate applications would be made for patents for such compositions.

The present application relates to one of the compositions so referred to, and it is designed for use in the process herein described in the making of light-green certaldite.

In carrying out the process referred to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such, by the use of suitable well-known tools. The gypsum employed may be the ordinary native gypsum of commerce, though I prefer that which is comparatively pure and free from other matters of different composition. Such gypsum is usually obtained hydrated, or containing a certain percentage of water in its composition; and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the whole of such water. This is done by subjecting it to the action of a graduallyincreasing heat, varying by preference with 'the size and quality of the material from 260 to 300 Fahrenheit for about twelve hours, or until the desired partial or complete dehydration is obtained. The length of time as well as the degree of heat required to effect this result will vary somewhat with the size, character, and purity of the gy 'isum employed; but the temperature should not exceed 500 Fahrenheit, and both it and the time of exposure should be regulated and limited with reference to securing uniformity of treatment throughout the whole mass or body. This operation may be known to be complete when a fractureot' a test block presents a uniform white color. Any suitable drying or baking apparatus may be employed for this purpose, many such being known in kindred branches of the arts; but it should be of such construction that the material under treatment shall not be brought into direct contact with the fire. When the desired dehydration has been effected the furnace is allowed to cool gradually, in Order that the material under treatment may be cooled gradually; or the material may be removed with due care to prevent breaking or exposure to moisture, and allowed to cool outside the furnace gradually until it is reduced in temperature sufiiciently to permit handling with safety in its subsequent treatment, which is designed to impart to it the desired color or tint and a high degree of insolubility and hardness throughout its mass. This step involves the use of the composition which forms the subject-matter of invention in the present application. This composition is formed of the following elements: water, by weight, two hundred parts; sulphate of copper, by weight, sixteen parts; ammonia, by weight, twenty parts. These ingredients, being mixed in about the proportions named, form a solution which is used as a bath, and to this end a suitable quantity of it is placed in a vesssl of proper shape to receive the article to be treated,which is dipped or immersed in the bath and subjected to its action until the article has acquired the desired degree of hardness and color. The length of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or solution, the porosity and nature or physical and chemical condition of the article; but usually twelve hours (more or less) will suffice; though to secure uniformity of treatment and of result through the whole body or mass of the article I prefer repeated dippings-two, three, or more-say two or three seconds at first, and increasing gradually to one, two, three or more minutes, more or less, with drying intervals of like increasing length between dippings, for half or three quarters of an hour or so, after which the ar- IOO ticle may remain in the bath for twelve hours or so.

While Ido not liinitmyinvention by any particular theory of chemical or physical reactions involved in the use of this bath as above described, I believe, with my present knowledge, that the salt (sulphate of copper) held in solution, by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the calcic sulphate and renders it more compact, harder, and less soluble, and that it has more or less a like indurating action upon the impurities or matters of other composition, (cflrbonates, &c.,) which are usually contained in greater or less quantities in native gypsums; also a portion of the sulphate of copper or of its elements combines or acts with the ammonia and imparts the desired light-green color to the calcic sulphate, which will usually be variegated more or less by irregular lines, veins, and markings of darkershades and other tints, due probably to impurities present in the gypsum. A highly-ornamental and beautifully- "ariegated light-green color will thus be secured, as well as such a degree of hardness, compactness, insolubility, and susceptibility of taking a high polish as renders the article (certaldite) an excellent and valuable substitute for marble, ornamental stones, tiles, &o., in the various uses to which they are applied in the arts.

When the article has been treated in the bath as above described it is removed and dried byexposure to the sun or to an equivalent furnaee-heat for one or two hours, or by ordinary atmospheric exposure for two or three days, when it is ready for polishing and such other manipulation as may best fit it for its jntended use, which may be done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications of the same, as circumstances may require, forms the subjectmatter of the first application herein referred to. Neither do I limit my present invention to the particular way herein described of applying it, though I now believe this Way or process to be the best. I also believe the proportions ofingredients which I have named in forming my improved composition to bethe best forthe purposes stated, and,among others, to secure a uniform degree of hardness and color throughout the mass of the article. It' the solution be very strong, there is great danger of rendering the surface of the article hard very quickly, and thereby preventing proper action of the bath upon theinterior substance of the article; or it the solution be very weak too much time is required, and even then a proper degree of hardness, density, and insolubility is not secured; also, by the conjoint ac tion of all the elements of the bath much better results are secured, especially upon native gypsums, than by a solution formed of part of the elements. For these reasons I prefer to employ all the elements of the composition in substantially the proportions named; but such limits, though ati'ording the best results, may be varied or exceeded somewhat and still obtain favorable results under skillful manipulation, and all such modifications employing the elements substantially as herein described in about the proportions set forth I consider as coming within my invention and claim.

I claim herein as my invention- The composition for treating dehydrated gypsum, consisting of water, sulphate of copper, and ammonia, substantially in the proportions hercinbet'ore described.

In testimony whereof I have hereunto set my hand.

RAPHAEL JOSIA. Witnesses:

GUIDO PANTALIONY, R. H. VHI'ITLESEY. 

